Candidatus Phytoplasma fraxini

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Candidatus Phytoplasma fraxini
Ashyellows.jpg
Death of white ash caused by Candidatus Phytoplasma fraxini
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Mycoplasmatota
Class: Mollicutes
Order: Acholeplasmatales
Family: Acholeplasmataceae
Genus: Candidatus Phytoplasma
Species:
Ca. P. fraxini
Binomial name
Candidatus Phytoplasma fraxini
Griffiths et al. 1999
Synonyms

Ash yellows phytoplasma

CandidatusPhytoplasma fraxini is a species of phytoplasma, a specialized group of bacteria which lack a cell wall and attack the phloem of plants. [1] This phytoplasma causes the diseases ash yellows and lilac witches' broom.

Contents

Taxonomy

Ca. Phytoplasma fraxini was first described in 1999 as the causal agent of ash yellows and lilac witches'-broom. [2] It belongs to the 16 Sr group VII, subgroup A. [3]

Distribution

The pathogen is found in Central and North Eastern USA and Central and Eastern Canada. [3] It was reported from Chile for the first time in 2011. [4] It was then reported from a range of trees in Colombia. [5] In 2017 it was reported infecting grapevine in Iran. [6]

Hosts

Ca. Phytoplasma fraxini can infect a wide range of species of Fraxinus (ash) including: white ash, narrow leaved ash, bunge ash, European ash, Oregon ash, black ash, manna ash, green ash, pumpkin ash, blue ash, Tianshan ash, Urapan and velvet ash. [3] A number of Syringa (lilac) species and hybrids are recorded as hosts including: Syringa x diversifolia, Syringa x henryi, Syringa x josiflexa, Hungarian lilac, nodding lilac, (cut-leaf lilac), Korean lilac, Syringa x nanceiana, Syringa oblata , Persian lilac , Syringa x prestoniae, Syringa pubescens , Chengtu lilac, Syringa tomentella , late lilac, common lilac and Yunnan lilac. [7]

In Canada, a few species of Prunus have been recorded as hosts: peach and Pembina plum. [8]

Diseases

Ash Yellows

Ash yellows
Ash Yellows Witches'-broom.jpg
Symptoms of ash yellows disease caused by Ca. Phytoplasma fraxini on green ash
Causal agentsCandidatus Phytoplasma fraxini
HostsAsh trees ( Fraxinus )
EPPO Code PHYPFR
TreatmentNone

This disease is relatively new so the disease cycle is mostly unknown, although it is thought that insect vectors are used as the mode of transmission. The disease is difficult to diagnose because some symptoms match those of stressed environmental conditions such as drought, flooding, or shallow soil. When trees become infected they can survive for many years or immediately die depending on the environmental conditions and health of the tree. [9] The major symptom of this disease is witches broom which causes branches in tufts. Unfortunately, there are not many strategies for controlling the disease besides avoiding areas where it is more prevalent.[ citation needed ]

Host and symptoms

Ash yellows refers to the disease that occurs on ash trees, usually white ash ( Fraxinus americana ) and green ash ( Fraxinus pennsylvanica ). [10] All ages and sizes of ashes are vulnerable to infection and symptoms will occur within three years of infection. [11] Some of these symptoms include progressive loss of vitality, subnormal growth, and leaves that fail to reach normal size and are often light green to chlorotic. [12] Additional symptoms include branch dieback, cracks in the bark, early color change in the fall, and premature death of trees. This disease is often diagnosed by the presence of a distinct symptom known as witches broom. [13] Witches broom occurs when there is an overgrowth of the branches of the host, resulting in a clumps of branches that resemble the head of a broom. This usually occurs near the soil line but can occur higher up in the tree as well.

Disease cycle

Not much is known about the disease cycle of ash yellows. It is unknown how exactly the Phytoplasma enters the tree and how it spreads but insect vectors are suspected. [13] This is due to the fact that Phytoplasmas are often spread in the salivary secretions of insects during feeding. [14] One likely candidate for spreading these Phytoplasmas, also known as Mycoplasma -like organisms (MLOs), is leafhoppers because data shows they are the most common insect vector for MLOs. [10] Once inside the host, the Phytoplasma attacks the tree's vascular system, specifically targeting the phloem sieve tubes. [15] Additionally, the severity of the disease symptoms caused by the Phytoplasma varies. In one study that was conducted, 12 different strains of Phytoplasmas belonging to the ash yellows group were tested and it was found that these strains varied significantly in aggressiveness and the impact they had on growth of the host. [16]

Environment

The disease typically occurs in woodlots and forests, home landscapes, and urban settings. The geographic origin of ash yellows is unknown but currently the disease is only reported to be in North America. [12] Some environmental factors that could contribute to the growth of the disease include mechanical damage, insect infestations, and fungi. [17] One major environmental condition that has been shown to amplify the growth of the disease includes drought. [10]

Management

There is no known way to cure ash yellows, so it is important to avoid growing ashes where ash yellows is prevalent. Some management strategies include promoting species diversity to reduce plant stress and limit competition among the ash trees. [10] In addition, it can be effective to remove infected trees with dieback and place irrigation systems so that during dry periods the ashes are not as susceptible to ash yellows. [18] One final control method is to use insecticide, however it is unclear if the use of insecticide to control leafhoppers is an effective way to prevent the spread of the Phytoplasma that causes ash yellows. [11]

Importance

Ash yellows has been found to be present in the U.S. as well as some parts of Canada. In one study, the ash yellows Phytoplasma was discovered in 102 out of 106 ash populations that were sampled from six US states and three Canadian provinces. [19] Within the ash populations that were sampled, 50% of the trees had crown die-back of 10% or more caused by ash yellows. [19] In a different study that looked at the annual increase of ash yellows in six populations of white ash in New York, the average annual increase in disease incidence was found to be 4.5%. [20] This study also found that disease incidence was lowest in the two populations where other plant species were present. [20] The reason that all of this is of importance is that wood from ash trees can be used to make a number of products including baseball bats and furniture. [21] In addition to this ash trees also provide food and habitat to a number of animals including cardinals and wood ducks. [21]

Lilac Witches'-broom

Lilac witches'-broom
Witchesbroom.jpg
Witches' broom from Syringa × prestonia
Causal agentsCandidatus Phytoplasma fraxini
Hosts Lilac
EPPO Code PHYPFR

Lilac witches’-broom (LWB) is a disease of lilacs caused by Candidatus Phytoplasma fraxini. This Phytoplasma was first identified as the causal agent of Ash yellows and has since been attributed to both diseases. [2]

Symptoms of the LWB Phytoplasma include witch's brooms, shortened internodes on new growth, twig dieback, overall loss of vitality and premature death. [22]

See also

Related Research Articles

<i>Fraxinus</i> Genus of plants

Fraxinus, commonly called ash, is a genus of plants in the olive and lilac family, Oleaceae, and comprises 45–65 species of usually medium-to-large trees, most of which are deciduous trees, although some subtropical species are evergreen trees. The genus is widespread throughout much of Europe, Asia, and North America.

<i>Fraxinus americana</i> Species of ash

Fraxinus americana, the white ash or American ash, is a fast-growing species of ash tree native to eastern and central North America.

<i>Phytoplasma</i> Genus of bacteria

Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-like organisms. Since their discovery, phytoplasmas have resisted all attempts at in vitro culture in any cell-free medium; routine cultivation in an artificial medium thus remains a major challenge. Phytoplasmas are characterized by the lack of a cell wall, a pleiomorphic or filamentous shape, a diameter normally less than 1 μm, and a very small genome.

<span class="mw-page-title-main">Citrus greening disease</span> Bacterial disease of citrus, bug-borne

Citrus greening disease or yellow dragon disease is a disease of citrus caused by a vector-transmitted pathogen. The causative agents are motile bacteria, Liberibacter spp. The disease is transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae, also known as the two-spotted citrus psyllid. It has no known cure. It has also been shown to be graft-transmissible.

<span class="mw-page-title-main">Acholeplasmataceae</span> Family of bacteria

Acholeplasmataceae is a family of bacteria. It is the only family in the order Acholeplasmatales, placed in the class Mollicutes. The family comprises the genera Acholeplasma and Phytoplasma. Phytoplasma has the candidatus status, because members still could not be cultured.

<i>Fraxinus pennsylvanica</i> Species of ash

Fraxinus pennsylvanica, the green ash or red ash, is a species of ash native to eastern and central North America, from Nova Scotia west to southeastern Alberta and eastern Colorado, south to northern Florida, and southwest to Oklahoma and eastern Texas. It has spread and become naturalized in much of the western United States and also in Europe from Spain to Russia.

<span class="mw-page-title-main">Aster yellows</span> Plant disease

Aster yellows is a chronic, systemic plant disease caused by several bacteria called phytoplasma. The aster yellows phytoplasma (AYP) affects 300 species in 38 families of broad-leaf herbaceous plants, primarily in the aster family, as well as important cereal crops such as wheat and barley. Symptoms are variable and can include phyllody, virescence, chlorosis, stunting, and sterility of flowers. The aster leafhopper vector, Macrosteles quadrilineatus, moves the aster yellows phytoplasma from plant to plant. Its economic burden is primarily felt in the carrot crop industry, as well as the nursery industry. No cure is known for plants infected with aster yellows. Infected plants should be removed immediately to limit the continued spread of the phytoplasma to other susceptible plants. However, in agricultural settings such as carrot fields, some application of chemical insecticides has proven to minimize the rate of infection by killing the vector.

<span class="mw-page-title-main">Elm yellows</span> Bacterial disease of elm trees

Elm yellows is a plant disease of elm trees that is spread by leafhoppers or by root grafts. Elm yellows, also known as elm phloem necrosis, is very aggressive, with no known cure. Elm yellows occurs in the eastern United States, and southern Ontario in Canada. It is caused by phytoplasmas which infect the phloem of the tree. Similar phytoplasmas, also known confusingly as 'Elm yellows', also occur in Europe. Infection and death of the phloem effectively girdles the tree and stops the flow of water and nutrients. The disease affects both wild-growing and cultivated trees.

<span class="mw-page-title-main">Grapevine yellows</span> Diseases associated to phytoplasmas

Grapevine yellows (GY) are diseases associated to phytoplasmas that occur in many grape growing areas worldwide and are of still increasing significance. The most important grapevine yellows is flavescence dorée.

Texas Phoenix palm decline, or lethal bronzing, is a plant disease caused by a phytoplasma, Candidatus Phytoplasma palmae. It takes its name from the state it was first identified in and the palm genus, Phoenix, upon which it was first identified. It is currently found in parts of Florida and Texas.

<span class="mw-page-title-main">Sugarcane grassy shoot disease</span> Phytoplasma (bacterial) disease

Sugarcane grassy shoot disease (SCGS), is associated with 'Candidatus Phytoplasma sacchari' which are small, pleomorphic, pathogenic mycoplasma that contribute to yield losses from 5% up to 20% in sugarcane. These losses are higher in the ratoon crop. A higher incidence of SCGS has been recorded in some parts of Southeast Asia and India, resulting in 100% loss in cane yield and sugar production.

Forest pathology is the research of both biotic and abiotic maladies affecting the health of a forest ecosystem, primarily fungal pathogens and their insect vectors. It is a subfield of forestry and plant pathology.

<i>Hymenoscyphus fraxineus</i> Fungus, cause of ash dieback

Hymenoscyphus fraxineus is an ascomycete fungus that causes ash dieback, a chronic fungal disease of ash trees in Europe characterised by leaf loss and crown dieback in infected trees. The fungus was first scientifically described in 2006 under the name Chalara fraxinea. Four years later it was discovered that Chalara fraxinea is the asexual (anamorphic) stage of a fungus that was subsequently named Hymenoscyphus pseudoalbidus and then renamed as Hymenoscyphus fraxineus.

<span class="mw-page-title-main">Cherry X Disease</span>

Cherry X disease also known as Cherry Buckskin disease is caused by a plant pathogenic phytoplasma. Phytoplasmas are obligate parasites of plants and insects. They are specialized bacteria, characterized by their lack of a cell wall, often transmitted through insects, and are responsible for large losses in crops, fruit trees, and ornamentals. The phytoplasma causing Cherry X disease has a fairly limited host range mostly of stone fruit trees. Hosts of the pathogen include sweet cherry, sour cherry, choke cherry, peaches, nectarines, almonds, clover, and dandelion. Most commonly the pathogen is introduced into economical fruit orchards from wild choke cherry and herbaceous weed hosts. The pathogen is vectored by mountain and cherry leafhoppers. The mountain leafhopper vectors the pathogen from wild hosts to cherry orchards but does not feed on the other hosts. The cherry leafhopper feeds on cherry trees and can transmit the disease from cherry orchards to peach, nectarine, and other economic crops. The Saddled Leafhopper is a vector of the disease in peaches. Control of Cherry X disease is limited to controlling the spread, vectors, and weed hosts of the pathogen. Once the pathogen has infected a tree it is fatal and removal is necessary to stop it from becoming a reservoir for vectors.

Little cherry disease or LChD, sometimes referred to as little cherry, K & S little cherry or sour cherry decline, is a viral infectious disease that affects cherry trees, most notably sweet cherries and sour cherries . Little cherry disease should not be confused with cherry buckskin disease, which is caused by Phytoplasma. Note that both diseases are among the diseases referred to as cherry decline.

<i>Longan witches broom-associated virus</i> Species of virus

Longan witches broom-associated virus is a species of positive-sense single-stranded RNA virus that has not been assigned to a genus within the family Potyviridae. It is thought to be the cause of witch's broom in longan, a large tropical tree from southeastern Asia of economic value. Longan witches broom disease is a condition that was first described in 1941. The virus was found in symptomatic plants and absent in healthy plants, but not all of Koch's postulates have been fulfilled.

<i>Fraxinus uhdei</i> Species of flowering plant

Fraxinus uhdei, commonly known as tropical ash or Shamel ash, is a species of tree native to Mexico and Central America. It is commonly planted as a street tree in Mexico and the southwestern United States. It has also been planted and spread from cultivation in Hawaii, where it is now considered an invasive species.

Milkweed yellows phytoplasma is a strain of phytoplasma in the class Mollicutes, a class of bacteria distinguished by the absence of a cell wall. The phytoplasma strain is denoted by the acronym MW1.

Candidatus Phytoplasma pruni is a species of phytoplasma in the class Mollicutes, a class of bacteria distinguished by the absence of a cell wall. The specific epithet pruni means "living on Prunus", emphasizing the fact that the phytoplasma is a parasite of various Prunus species, otherwise known as stone fruits. The phytoplasma is commonly called the X-disease phytoplasma.

References

  1. ↑ Derickx, Lisa M.; Antunes, Pedro M. (2013). A Guide to the Identification and Control of Exotic Invasive Species in Ontario's Hardwood Forests (PDF). Sault Ste. Marie, Ontario: Algoma University. ISBN   9780929100210. Archived (PDF) from the original on 21 November 2014. Retrieved 21 November 2014.
  2. 1 2 M. Griffiths, Helen; Wayne A. Sinclair; Christine D. Smart; Robert E. Davis (1999). "The Phytoplasma associated with ash yellows and lilac witches'-broom: 'Candidatus Phytoplasma fraxini '". International Journal of Systematic and Evolutionary Microbiology . 49 (4): 1605–1614. doi: 10.1099/00207713-49-4-1605 . PMID   10555342.
  3. 1 2 3 Tuffen, MG (January 2016). "Rapid Pest Risk Analysis (PRA) for:'Candidatus Phytoplasma fraxini'". Defra . Retrieved 26 August 2018.
  4. ↑ Arismendi, N; Gonzalez, F; Zamorano, A; Andrade, N; Pino, AM; Fiore, N (2011). "Molecular identification of 'Candidatus Phytoplasma fraxini' in murta and peony in Chile". Bulletin of Insectology. 64: S95–S96.
  5. ↑ Franco-Lara, Liliana; Perilla Henao, Laura Margarita (2014). "Phytoplasma diseases in trees of Bogotá, Colombia: a serious risk for urban trees and crops" . Retrieved 28 August 2018.
  6. ↑ Ghayeb Zamharir, Maryam; Paltrinieri, Samanta; Hajivand, Shokrollah; Taheri, Mahdi; Bertaccini, Assunta (2017). "Molecular identification of diverse 'Candidatus Phytoplasma' species associated with grapevine decline in Iran". Journal of Phytopathology. 165 (7–8): 407–413. doi:10.1111/jph.12574. hdl:11585/617853. ISSN   0931-1785.
  7. ↑ Sinclair, WA; Griffiths, HA; Davis, RE (1996). "Ash yellows and lilac witches'-broom: phytoplasmal diseases of concern in forestry and horticulture". Plant Disease. 80 (5): 468–475. doi:10.1094/PD-80-0468 . Retrieved 31 August 2018.
  8. ↑ Zunnoon-Khan, S.; Arocha-Rosete, Y.; Scott, J.; Crosby, W.; Bertaccini, A.; Michelutti, R. (2010). "First report of 'Candidatus Phytoplasma fraxini' (group 16SrVII phytoplasma) associated with a peach disease in Canada". Plant Pathology. 59 (6): 1162. doi:10.1111/j.1365-3059.2010.02355.x. ISSN   0032-0862. S2CID   86008796.
  9. ↑ White-MacDougall, Wendy (May 1999). "Three Ash Diseases You Should Know". Forest Insect and Disease Newsletter. Retrieved 21 November 2014.
  10. 1 2 3 4 Pokorny, Jill D.; Sinclair, Wayne A. (1994). "How to Identify and Manage Ash Yellows in Forest Stands and Home Landscapes" (PDF). Radnor, Pennsylvania: United States Forest Service, Northern Area State & Private Forestry. NA-FR-03-94. Retrieved 5 December 2014.{{cite journal}}: Cite journal requires |journal= (help)
  11. 1 2 Olis, Jim; Hudelson, Brian (6 August 2012). "Ash Yellows". Wisconsin Horticulture. University of Wisconsin–Extension Cooperative Extension. XHT1079. Retrieved 5 December 2014.
  12. 1 2 Matteoni, J. A.; Sinclair, W. A. (1988). "Elm Yellows and Ash Yellows". In Hiruki, Chuji (ed.). Tree Mycoplasmas and Mycoplasma Diseases. Edmonton, Alberta: University of Alberta Press. pp. 21–23. ISBN   9780888641267 . Retrieved 5 December 2014.
  13. 1 2 Agrios, George N. (2005). Plant Pathology (5th ed.). Burlington, Massachusetts: Elsevier Academic Press. ISBN   9780120445653.
  14. ↑ Olivier, Chrystel Y.; Lowery, D. Thomas; Stobbs, Lorne W. (October 2009). "Phytoplasma diseases and their relationships with insect and plant hosts in Canadian horticultural and field crops". The Canadian Entomologist. 141 (5): 425–462. doi:10.4039/n08-CPA02. S2CID   85039968.
  15. ↑ IRPCM Phytoplasma/Spiroplasma Working Team – Phytoplasma taxonomy group (July 2004). "'Candidatus Phytoplasma', a taxon for the wall-less, non-helical prokaryotes that colonize plant phloem and insects". International Journal of Systematic and Evolutionary Microbiology. 54 (4): 1243–1255. doi: 10.1099/ijs.0.02854-0 . PMID   15280299 . Retrieved 5 December 2014.
  16. ↑ Sinclair, W. A.; Griffiths, H. M. (March 2000). "Variation in Aggressiveness of Ash Yellows Phytoplasmas". Plant Disease. 84 (3): 282–288. doi: 10.1094/PDIS.2000.84.3.282 . PMID   30841242.
  17. ↑ "Ash Yellows and Decline". Missouri Botanical Garden. Saint Louis, Missouri. Retrieved 5 December 2014.
  18. ↑ Gillman, Daniel H. (September 2011). "Ash Yellows". Publications & Resources. Amherst, Massachusetts: University of Massachusetts Extension Landscape, Nursery and Urban Forestry Program. Archived (PDF) from the original on 5 December 2014. Retrieved 5 December 2014.
  19. 1 2 Sinclair, W. A.; Griffiths, H. M. (1995). "Epidemiology of a Slow-Decline Phytoplasmal Disease: Ash Yellows on Old-Field Sites in New York State" (PDF). Phytopathology. 85: 123–128. doi:10.1094/Phyto-85-123. Archived (PDF) from the original on 22 May 2014. Retrieved 5 December 2014.
  20. 1 2 Walla, J. A.; Jacobi, W. R.; Tisserat, N. A.; Harrell, M. O.; Ball, J. J.; Neill, G. B.; Reynard, D. A.; Guo, Y. H.; Spiegel, L. (March 2000). "Condition of Green Ash, Incidence of Ash Yellows Phytoplasmas, and Their Association in the Great Plains and Rocky Mountain Regions of North America". Plant Disease. 84 (3): 268–274. doi: 10.1094/PDIS.2000.84.3.268 . PMID   30841240.
  21. 1 2 Engstrom, Shari. "Importance of Ash Trees". Garden Guides. Retrieved 5 December 2014.
  22. ↑ L. Fiala, John; Vrugtman, Freek (2008). "Lilac diseases, pests and problems.". Lilacs: a gardener's encyclopedia. Timber Press. p. 234. ISBN   978-0-88192-795-5 . Retrieved 29 October 2010.
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